Differential feed roll crimper and method



June 11, 1968 TRIFUNOVIC ET AL 3,387,349

DIFFERENTIAL FEED ROLL CRIMPER AND METHOD 2 Sheets-Sheet 1 Filed April8, 1965 u may INVENTORS ALfXANDE'E L.

ATTORNEY 2 Sheets-Sheet 2 INVENTORS ALEXH/Vfifl? L. TR/FZ/NOV/C ATTORNEY June 11, 1968 A. L TRIFUNOVIC ET AL DIFFERENTIAL FEED ROLL CRIMPERAND METHOD Filed April 8, 1965 United States Patent 3,387,349DIFFERENTIAL FEED ROLL CRIMPER AND METHOD Alexander L. Trifunovic andSteve E. Zeis, Wilmington, Del., assignors to Joseph Bancroft & SonsCompany,

Wilmington, Del., a corporation of Delaware Filed Apr. 8, 1965, Ser. No.446,555

17 Claims. (Cl. 23-1) ABSTRACT OF THE DISCLOSURE Yarn crimping apparatushaving a pair of feed rolls driven at different peripheral speeds, oneof which is provided with grooves and ridges for forming a coil crimp inthe yarn fed therebetween. In one embodiment, the feed rolls aredisposed to feed yarn into the stutter crimper having a crimping chamberin which the yarn is folded over and crimped so as to superimpose astuifer crimper on the coil crimp.

This invention relates to yarn crimping apparatus and methods and moreparticularly to a method and apparatus for imparting a helical crimp toyarns composed of synthetic, thermoplastic material.

An object of the invention is to provide a method and apparatus of theabove type having novel and improved characteristics.

Another object is to provide a synthetic, thermoplastic yarn havingnovel and improved crimp characteristics.

Another object is to provide a yarn or filament having successive thickand thin portions disposed to minimize the slippage of the yarn orfilament along adjacent yarns or filaments when Woven into a fabric.

Another object is to provide a yarn or filament having a contouredsurface.

Various other objects and advantages will be apparent from the followingdescription, taken in connection with the accompanying drawings in whicha specific embodiment has been set forth for purposes of illustration.

In one embodiment of the invention the yarn to be processed is passedover a preheater into the bite of a pair of feed rolls which areoperated at different speeds. The slower roll may be formed withtransverse ridges and grooves on its peripheral surface. These groovesare formed by a milling tool or a grinder which is moved transversely ofthe peripheral surface, preferably in a direction parallel to the axisof the roll or at a slight angle thereto while the roll is indexedbetween successive passes of the tool. The faster roll is formed with asmooth surface or with a surface which is sandblasted for increasing thefriction on the yarn.

The preheater preferably heats the yarn to a temperature slightly belowthe softening temperature without rendering the yarn tacky so thatcrimping is facilitated. The differential effect of the feed rollsintroduces stresses in the yarn which cause the yarn to assume a helicalform when relaxed. The helix, however, is somewhat irregular andreverses in direction at irregular intervals along the length of theyarn.

During the crimping operation the transverse ridges on the slow rollserve to form indentations along the surface of the yarn so that theyarn has alternate thick and thin areas which impart a novelty effect tothe yarn.

In order to prevent the yarn from wrapping around the grooved feed rolla rubber surfaced take-off roll is provided. The yarn may be slightlycooled to eliminate tackiness While on the take-off roll and is thenpassed through a heating zone in tensionless state to relax the yarn andallow the crimp to form after which it is cooled and wound as on a ringtwister.

In the drawings:

FIG. 1 is a side elevation of an apparatus according to the invention,with parts in section for clarity;

FIG. 2 is a partial transverse section taken on the line 2- 2 of FIG. 1showing the construction of the preheater;

FIG. 3 is a broken detail view of the feed rolls;

FIG. 4 is a greatly magnified elevation of a yarn produced by thepresent invention;

FIG. 5 is a further detail of the yarn on a still larger scale; and

FIG. 6 is a side elevation partly in section showing a stuffer crimperembodying the present invention.

Referring to FIGS. 1-3 more in detail, the invention is shown asembodied in an apparatus comprising a frame 11 having an arm 12 on whicha cop 13 is mounted. Yarn 14 from the cop 13 is fed over a guide rod 15through a tension device 16 and over a guide rod 17 to a preheater 18.The preheater comprises a block 20 having a heater element 21 thereinand having an arcuate surface 22 formed with an open longitudinal groove23 in which the yarn. 14 lies as it is fed along and in contact with theheated surface. The heater block 20 is carried on a support 24 attachedto the base 11.

From the heater block 20 the yarn passes to the bite of the pair of feedrolls 31 and 32 which are mounted on shafts 33 and 34 respectively anddriven at different speeds by meshing gears 35 and 36. In the form shownthe feed roll 31 is mounted in bearing blocks 37 only one of which isshown and are slidable in frame 11 and are spring-pressed into feedingengagement with the yarn by springs 39. The spring pressure isadjustable by adjusting screws 40. The roll 32 is mounted in fixedbearings 41.

The surface of the roll 31 which is the faster roll may be smooth or maybe finely sandblasted to improve its grip on the yarn. The peripheralsurface of the roll 32 is formed with transverse ridges 42 and grooves43 which extend in a direction parallel to the axis of the roll or at aslight angle thereto. These grooves 43 are closely spaced and are of theorder of .0007 inch. The grooves may be formed by milling or grinding orby being impressed from a master roll.

The curved surface 22 of the heater block 20 is extended to form a tip45, the end of which is disposed within and closely adjacent the bite ofthe feed rolls 31 and 32 so that the yarn is discharged directly fromthe heated surface into the bite of the feed rolls without appreciablecooling. After emerging from the bite of the feed rolls the yarn 14passes around a take-off roll 51 which may have a soft surface 52 suchas natural or synthetic rubber. This roll 51 is mounted on a shaft 53and is held in pressure contact with and driven by the grooved roll 32.

A blast of cooling air is applied to the yarn on the take-off roll 51from an air jet 54 which is mounted above the rolls and is connected toa source of cooling air by a hose 55. This cooling air is only used ifthe yarn is in tacky state when discharged from the bite of the rolls 31and 32 and is intended to prevent the yarn from sticking to the surfaceof the take-off roll 51. Obviously the cooling air may be omitted if notrequired in any particular instance.

From the take-01f roll the yarn passes into the bore 56 of a heatingblock 57 carrying a heating element 5%. The bore 56 is of a diametersuch that the yarn hangs freely therein, out of contact with thesurfaces of the block and is free to coil in tensionless state into asuccession of helical loops 59.

From the heater block 57 the yarn passes along an air path of sufiicientlength to allow the yarn to cool to set the crimp, thence between a pairof delivery rolls 61 and through a pigtail 62 to the traveller 63 of aring twister 64 having a spindle 65 carrying a winding 66. The deliveryrolls are driven at a speed such that the yarn is held is tensionlessstate in the heating and cooling zones but is fed to the twister under acontrolled tension for twisting and winding.

Obviously, if the nature of the yarn is such that it does not tend towrap around the feed roll the take-off roll may be omitted and the yarnfed directly from the feed rolls to the post heater. Also the postheater can be omitted if the yarn as discharged from the feed rolls isin a relaxed state such that the crimp becomes set in its path to thewinder.

The coil type crimp can be varied as to coil dimension and frequency byvarying the speed ratios of the feed rolls and by varying the surfacecharacteristics. A speed ratio of the order of 2:1 to 3:1 has been foundsatisfactory for small denier monofilament nylon yarn of the size usedfor ladies sheer hosiery. The grooved surface of the roll 32 improvesthe crimp characteristics and provides a yarn having successive thickportions 70 and intervening thin or grooved portions 71. Smooth surfacedrolls may, however, be used if other yarn characteristics are desired.

In some instances the rolls 31 and 32 may be used for forming apatterned or embossed effect upon the yarn without introducing thecrimping effect. For this purpose the rolls may be operated at the sameperipheral speed so that the pattern on the surface of the feed roll isimpressed into the filament while the filament is somewha flattened dueto the pressure of the roll 32.. This operation may be facilitated bypassing the filament first over the preheater for heating the filamentto a softening temperature. The imprint of the roll 32 is set into theflattened yarn as the yarn cools after leaving the bite of the rolls.

In the embodiment of FIG. 6 the yarn 75 is Withdrawn from a cop 76through an adjustable tension gate 77 and passes in an arcuate pathalong a slot 79 in a heated block 80.

A stuffer crimper composed of a block 81 heated by suitable means suchas Cairods 82 is formed with a vertical bore carrying a crimping tube 33which forms an elongated crimping chamber. A pair of feed rolls and S5,driven at the same peripheral speed by gears 36 and 37 are disposed atthe lower end of the tube 83 and are adapted to feed the yarn into thetube to be folded over and crimped against the mass of crimped yarn heldconfined in the tube and to be advanced along the tube by the pressureexerted by the feed rolls.

A third roll 9% is disposed below and in peripheral contact with thefeed roll 8- and is driven at a higher periperul speed by gears 88 and91. The feed roll 84 is formed with a fluted or grooved surface similarto roll 32 of FIG. 1.

The yarn 75 is discharged directly from the heated surface of the block8t directly into the bite between the feed roll 84 and the third roll 90where the yarn is distorted and crimped as in the embodiment of FlGS. lto 5. From the bite of the feed roll 84 and the third roll 90 the yarnpasses around a portion of the periphery of the roll 84 to the bitebetween the feed rolls 34 and 85 where it is fed into the stuttercrimper and a second crimp is superimposed on the first crimp to form arandomly crimped and bulked yarn.

In this embodiment the third roll 90 is driven at a speed slightly inexcess of the speed of the feed roll 84. For example, the speed of thefeed roll 90 may be of the order of above that of the feed roll 84. Theamount of overfeed is restricted to a value such that the yarn is pickedup by the feed rolls 84 and 85 without forming an excessive amount ofslack between the bites of the third roll 90 and of the feed roll 85with the feed roll 84.

It has also been found that roll 99 can be eliminated in some cases andfeed rolls 84 and 85 driven at different peripheral speeds to producethe crimped effect.

The crimped yarn is removed from the upper end of the crimping tube byany suitable means not shown or may d be discharged in the form of apacked core as shown in US. Patent No. 2,997,747.

In this embodiment the yarn has thick and thin portions and is coiled asin FIGS. 4 and 5 and in addition has sawtooth crimps characteristic ofthe criznps produced in a stulfer crimper.

What is claimed is:

1. Apparatus for crimping yarn comprising a pair of feed rolls betweenwhich said yarn is fed, one of said feed rolls having a peripheralsurface formed by successive grooves and ridges, means driving said feedrolls at different peripheral speeds for thereby forming coil crimp insaid yarn and means for taking up said yarn after passage between saidfeed rolls.

2. Apparatus as set forth in claim 1 in which preheating means isprovided to preheat the yarn as it is fed to the bite of said feedrolls.

3. Apparatus as set forth in claim 1 in which a take-off roll isdisposed in contact with the surface of one of said feed rolls forstripping the crimped yarn from said feed rolls.

4. Apparatus as set forth in claim 3 in which said till-1B- off roll isformed with a soft surface.

5. Apparatus as set forth in claim 4 in which said take- 01? roll isdriven by surface contact with said feed roll.

6. Apparatus as set forth in claim 3 in which means is provided tosupply cooling air to the yarn on said takeoff roll for cooling the sameto a non-tacky state thereon.

7. Apparatus as set forth in claim 1 in which a pair of delivery rollsis disposed to maintain the yarn in tensionless state for crimping, saiddelivery rolls being spaced from said feed rolls to provide a heatingzone and a coo1- ing zone therebetween whereby the yarn is crimped andcrimp set prior to winding.

3. Apparatus as set forth in claim 1 in which said grooves and ridgesextend at a slight angle to the axis of said feed roll.

9. The method of crimping yarn which comprises feeding said yarn betweena pair of feed rolls having different peripheral speeds, one of which isprovided with a transversely grooved surface, and withdrawing the yarnfrom the bite of said rolls.

It The method set forth in claim 9 in which said yarn is preheated inadvance of said rolls.

11. A method set forth in claim 9 in which the yarn is passed intensionless state through a relaxing zone after passing between saidrolls.

12. Crimping apparatus comprising an elongated crimping chamber, a pairof feed rolls having a bite disposed to feed yarn for crimping into oneend of said chamber, to be folded over and crimped against a mass ofpreviously crimped yarn held compacted in said chamber, and a third rollpositioned to engage and grip the yarn on one of said feed rolls inadvance of the bite of said feed rolls, means driving said feed rolls atthe same peripheral speed, means driving said third roll at a higherperipheral speed for thereby forming a coil crimp in the yarn in ad-Vance of said bite.

13. Crimping apparatus as set forth in claim 12 in which said one ofsaid feed rolls is for-med with a grooved surface adapted to form thickand thin portions in the yarn.

14. Crimping apparatus as set forth in claim 12 in which preheatingmeans is provided for heating the yarn in advance of said rolls.

15. Apparatus as set forth in claim 12 in which heating means isprovided for heating the crimped yarn in said crimping chamber forheat-setting the crimp therein.

16. Crimping apparatus comprising an elongated crimping chamber, a pairof feed rolls having a bite disposed to feed yarn for crimping into oneend of said chamber, to be folded over and crimped against a mass ofpreviously crimped yarn held compacted in said chamber, and meansdriving said feed rolls at different peripheral speeds for therebyintroducing a coil crimp into the yarn which is fed into said crimpingchamber.

17. Apparatus as set forth in claim 16 in which one of said feed rollsis formed with a peripheral surface having successive grooves andridges.

Kurzke et a1 28--72 Smith 264-282 Irwin et a1 28-1 Shattuck 28-72Rosenstein 28-72 LOUIS K. RIMRODT, Primary Examiner.

